Mechanical cutting system for surgical forceps

ABSTRACT

A surgical instrument includes a housing having an elongated shaft that extends therefrom and a handle pivotable relative thereto. An end effector assembly is attached to a distal end of the shaft and includes first and second jaw members. The first jaw member is pivotably attached to a distal end of the shaft and the second jaw member extends along a longitudinal axis defined therethrough and fixed to the distal end of the shaft by a living hinge. The first jaw member, upon actuation of the handle, is movable relative to the second jaw member between spaced-apart position, an approximated position for grasping tissue, and a second position for over-compressing tissue grasped between jaw members. A knife is disposed within a channel defined within the second jaw member and is exposed to cut tissue when the first jaw member over-travels to over-compress the second jaw member.

BACKGROUND

1. Technical Field

The present disclosure relates to surgical instruments and, moreparticularly, to surgical forceps having mechanical cuttingcapabilities.

2. Background of Related Art

Many surgical instruments include one or more movable handles, levers,actuators, triggers, etc. for actuating and/or manipulating one or morefunctional components of the surgical instrument. For example, asurgical forceps may include a movable handle that is selectivelycompressible relative to a stationary handle for moving first and secondjaw members of the forceps between spaced-apart and approximatedpositions for grasping tissue therebetween. Such a forceps may furtherinclude additional components such as a trigger for selectivelydeploying a knife between the jaw members to cut tissue graspedtherebetween.

As can be appreciated, as additional functional components are added tothe surgical instrument, additional deployment structures or deploymentstructures capable of actuating more than one component are required.However, multiple deployment structures and/or combined deploymentstructures may be limited by spatial constraints within the housing ofthe surgical instrument and/or functional constraints of the components.

SUMMARY

As a result there exists a need to provide a simple yet effectivecutting mechanism for surgical instruments that alleviates the need foradditional spatial considerations in the housing. As used herein, theterm “distal” refers to the portion that is being described that isfurther from a user, while the term “proximal” refers to the portionthat is being described that is closer to a user. Further, to the extentconsistent, any of the aspects described herein may be used inconjunction with any of the other aspects described herein.

The present disclosure relates to a surgical instrument having a housingwith an elongated shaft that extends therefrom and a handle pivotablycoupled to the housing and moveable relative thereto. The surgicalinstrument also includes an end effector assembly having first andsecond jaw members, the first jaw member pivotably attached to a distalend of the shaft and the second jaw member extending along alongitudinal axis defined therethrough and fixed to the distal end ofthe shaft by a living hinge. The first jaw member, upon actuation of thehandle relative to the housing, is movable relative to the second jawmember between a spaced-apart position, an approximated position forgrasping tissue between the first and second jaw members, and a secondposition for providing an over-compressive force to the jaw members. Aknife is disposed within a channel defined within the second jaw member.

When the handle is initially actuated relative to the housing, the firstjaw member is moved from the spaced-apart position to the approximatedposition to grasp tissue between jaw members. When the handle is furtheractuated from the approximated position to the second position, thefirst jaw member over-travels past the longitudinal axis toover-compress the jaw members and the second jaw member deflectsrelative to the longitudinal axis against the bias of the living hingethereby exposing the knife from the channel to cut tissue graspedbetween jaw members.

In one embodiment according to the present disclosure, the surgicalinstrument includes a drive rod that extends through the shaft having adrive pin at a distal end thereof. Actuation of the drive rod moves thefirst jaw member relative to the second jaw member. The first jaw memberincludes a flange that extends proximally therefrom having an aperturedefined therein for receiving a pivot pin. The first jaw member isrotatable about the pivot pin upon actuation of the drive rod. Theflange includes a cam slot defined therein configured to receive thedrive pin to move the first jaw member relative to the second jawmember.

In one embodiment according to the present disclosure, in theapproximated position, the jaw members grasp tissue with a clampingpressure in the range of about 3 kg/cm² to about 16 kg/cm². In yetanother embodiment, when the clamping pressure between jaw membersexceeds 16 kg/cm², the second jaw member deflects relative to thelongitudinal axis to expose the knife.

In still another embodiment according to the present disclosure, thefirst jaw member includes a channel defined therein in verticalregistration with the channel defined within the second jaw member. Thechannel defined in the first jaw member is configured to receive theknife as the first jaw member over-travels past the longitudinal axisand the second jaw member deflects about the living hinge. In yetanother embodiment, the over-travel of the first jaw member against thesecond jaw member causes the second jaw member to deflect in atip-biased manner thereby initially exposing a distal end of the knifeand cutting tissue in a distal-to-proximal manner as the knife isfurther exposed.

The present disclosure also relates to a surgical instrument having anend effector assembly including first and second jaw members. The firstjaw member is pivotable relative to the second jaw member and the secondjaw member extends along a longitudinal axis defined therethrough. Thesecond jaw member includes a living hinge at a proximal end thereof. Thefirst jaw member is movable relative to the second jaw member between aspaced-apart position, an approximated position for grasping tissuebetween the first and second jaw members, and a second position forproviding an over-compressive force to the jaw members. A knife isdisposed within a channel defined within the second jaw member.

When the first jaw member is moved from the spaced-apart position to theapproximated position to grasp tissue between jaw members, and furthermoved from the approximated position to the second position toover-compress the jaw members, the first jaw member over-travels pastthe longitudinal axis and the second jaw member deflects relative to thelongitudinal axis against the bias of the living hinge thereby exposingthe knife from the channel to cut tissue grasped between jaw members.

In one embodiment, the jaw members grasp tissue with a clamping pressurein the range of about 3 kg/cm² to about 16 kg/cm². In yet anotherembodiment, when the clamping pressure between jaw members exceeds 16kg/cm², the second jaw member deflects relative to the longitudinal axisto expose the knife.

In yet another embodiment, the first jaw member includes a channeldefined therein in vertical registration with the channel defined withinthe second jaw member. The channel defined in the first jaw member isconfigured to receive the knife as the first jaw member over-travelspast the longitudinal axis and the second jaw member deflects about theliving hinge.

In still another embodiment, the over-travel of the first jaw memberagainst the second jaw member causes the second jaw member to deflect ina tip-biased manner thereby initially exposing a distal end of the knifeand cutting tissue in a distal-to-proximal manner as the knife isfurther exposed.

The present disclosure also relates to a method for treating and cuttingtissue, actuating a handle of a surgical instrument to grasp tissuebetween a pair of first and second jaw members of an end effectorassembly under a first pressure. The method also includes applyingelectrosurgical energy to the jaw members to treat tissue graspedbetween the end effectors and further actuating the handle to cause thefirst jaw member to over-travel past a longitudinal axis defined throughthe second jaw member and over-compress the jaw members thus causing thesecond jaw member to deflect about a living hinge relative to thelongitudinal axis and expose a knife for severing tissue grasped betweenthe jaw members.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure are described herein withreference to the drawings wherein like reference numerals identifysimilar or identical elements:

FIG. 1 is a front, perspective view of an endoscopic surgical forcepsconfigured for use in accordance with the present disclosure;

FIG. 2A is a side view of an end effector assembly of the surgicalforceps according to the present disclosure having first and second jawmembers shown in a spaced-apart position;

FIG. 2B is a side view of the end effector assembly of FIG. 2A with thefirst and second jaw members shown in an approximated position;

FIG. 2C is a side view of the end effector assembly of FIG. 2A with thefirst and second jaw members shown in an over-compressed position;

FIG. 2D is a side view of the second or fixed jaw member of the endeffector assembly of FIG. 2A showing exposure of a knife upon deflectionof the second or fixed jaw member; and

FIG. 3 is a schematic illustration of a robotic system configured foruse in accordance with the present disclosure.

DETAILED DESCRIPTION

Referring generally to FIG. 1, a forceps provided in accordance with thepresent disclosure is shown generally identified by reference numeral10. Forceps 10, as will be described below, may be configured to operatein both a bipolar mode, e.g., for grasping, treating, and/or dissectingtissue, and a monopolar mode, e.g., for treating and/or dissectingtissue. Although the present disclosure is shown and described withrespect to forceps 10, the aspects and features of the presentdisclosure are equally applicable for use with any suitable surgicalinstrument or portion(s) thereof for selectively actuating, moving,and/or deploying the assemblies and/or components of the surgicalinstrument. Obviously, different connections and considerations apply toeach particular instrument and the assemblies and/or components thereof;however, the aspects and features of the present disclosure remaingenerally consistent regardless of the particular instrument,assemblies, and/or components provided.

Continuing with reference to FIG. 1, forceps 10 includes a housing 20, ahandle assembly 30, a rotating assembly 70, and an end effector assembly100 including first and second jaw members 110 and 120, respectively.Forceps 10 further includes a shaft 12 having a distal end 14 configuredto mechanically engage end effector assembly 100 and a proximal end 16that mechanically engages housing 20. Forceps 10 also includes anelectrosurgical cable 2 that connects forceps 10 to a generator (notshown) or other suitable power source, although forceps 10 mayalternatively be configured as a battery powered instrument. Cable 2includes wires (not shown) extending therethrough that have sufficientlength to extend through shaft 12 in order to provide electrical energyto at least one electrically-conductive surface 112, 122 (FIG. 2A) ofjaw members 110, 120, respectively, of end effector assembly 100, e.g.,upon activation of a switch 4. Other suitable ways of delivering energyto the electrically-conductive surfaces 112, 122 are contemplatedincluding other suitable power sources, e.g., forceps 10 mayalternatively be configured as a battery-powered forceps 10. Rotatingassembly 70 is rotatable in either direction to rotate end effectorassembly 100 relative to housing 20. Housing 20 houses the internalworking components of forceps 10, which are described in detail below.

Referring to FIGS. 2A-2D, end effector assembly 100 is attached at adistal end 14 of shaft 12 and includes opposing jaw members 110, 120pivotably coupled to one another. Each of the jaw members 110 and 120includes a jaw body 111, 121 supporting the respectiveelectrically-conductive surface 112, 122, and a respectiveproximally-extending jaw flange 114, 124. Flanges 114, 124 are pivotablycoupled to one another about a pivot 75 to permit movement of jawmembers 110, 120 relative to one another between a spaced-apart position(FIG. 2A), an approximated position (FIG. 2B) for grasping tissuebetween surfaces 112, 122 and an over-compressed position (FIG. 2C) fordeploying a knife 184. More details with respect to the actuation of thejaw members 110 and 120 are explained below.

One or both of surfaces 112, 122 are adapted to connect to a source ofenergy (not explicitly shown), e.g., via the wires (not shown) of cable2 (FIG. 1) and are configured to conduct energy through tissue graspedtherebetween to treat, e.g., seal, tissue. More specifically, endeffector assembly 100 defines a bipolar configuration wherein surface112 is charged to a first electrical potential and surface 122 ischarged to a second, different electrical potential such that anelectrical potential gradient is created for conducting energy betweensurfaces 112, 122 and through tissue grasped therebetween for treatinge.g., sealing, tissue. Activation switch 4 (FIG. 1) is operably coupledbetween the source of energy (not shown) and surfaces 112, 122, thusallowing the user to selectively apply energy to surfaces 112, 122 ofjaw members 110, 120, respectively, of end effector assembly 100 whenactivated.

End effector assembly 100 is designed as a unilateral assembly, i.e.,where jaw member 120 is relatively fixed relative to shaft 12 and jawmember 110 is movable relative to shaft 12 and fixed jaw member 120. Jawmember 120 is attached to a distal end of jaw flange 124 by a livinghinge 127 which is configured to allow the jaw member 120 to deflectrelative to a longitudinal axis “A” defined along jaw member 120 whenenough pressure is exerted on jaw member 120 by jaw member 110 (See FIG.2C). A knife channel 129 is defined within jaw member 120 to house theknife 184 therein and permit deployment of the knife 184 therefrom asexplained in more detail below.

With reference again to FIG. 1, handle assembly 30 includes a movablehandle 40 and a fixed handle 50. Fixed handle 50 is integrallyassociated with housing 20 and movable handle 40 is movable relative tofixed handle 50. Movable handle 40 is movable relative to fixed handle50 between an initial position, wherein movable handle 40 is spaced fromfixed handle 50, a first compressed position, wherein movable handle 40is compressed towards fixed handle 50, and a second compressed positionwherein moveable handle 40 is further compressed relative to handle 50.A biasing member (not shown) may be provided to bias movable handle 40towards the initial position. Movable handle 40 is ultimately connectedto a drive assembly (not explicitly shown) which ultimately impartsmovement of a drive rod 85 which, in turn, moves the jaw members 110,120 between the spaced-apart position (FIG. 2A), corresponding to theinitial position of movable handle 40, and the approximated position(FIG. 2B), corresponding to an initial compressed position of movablehandle 40, and an over-compressed position (FIG. 2C) corresponding to asecond compressed position of handle 40. Any suitable drive assembly forthis purpose may be provided.

As best shown in FIGS. 2A-2C, the corresponding flanges 114 and 124 ofrespective jaw members 110 and 120 each include a cam slot 115 and 125defined therein configured to commonly receive a drive pin 80 attachedto a distal end of the drive rod 85. Movement of the handle 40 from theinitial position to the initial compressed position and potentially thesecond compressed position, in turn, translates the drive bar 85 and thedrive pin 80 to correspondingly actuate the jaw members 110 and 120.More particularly, upon actuation of handle 40, the drive pin 80 ispulled proximally within the corresponding cam slots 115 and 125 to camthe jaw member 110 towards the approximated position (FIG. 2B) with jawmember 120 which enables a user to grasp and treat tissue. In thisposition, the jaw members 110 and 120 are parallel to the longitudinalaxis “A” defined through jaw member 120. For example, when sealingtissue, the jaw members 110 and 120 when approximated may be configuredto provide an initial clamping pressure on tissue within the range ofabout 3 kg/cm² to about 16 kg/cm². A specific gap distance between jawmembers may facilitate and enhance the sealing process, e.g., a gapwithin the range of about 0.001 inches to about 0.006 inches.

As best shown in FIG. 2C, when the handle 40 is moved to the secondcompressed position, the drive pin 80 applies an over-compressive forceto the jaw members 110 and 120 which provides greater pressure betweenjaw members 110 and 120 and causes jaw member 110 to over-travel and jawmember 120 to deflect about the living hinge 127 to an angle α relativeto the longitudinal axis “A”. As used herein, the term over-travel isdefined to mean that the jaw member 110 travels past parallel with jawmember 120 due to the over-compressive force applied by handle 40. Asused herein, the term over-compress is used to define a force beyond thenormal compressive forces against tissue associated with tissue sealing(in the range of about 3 kg/cm² to about 16 kg/cm²). In the embodimentsdescribed herein, the over-compressive force applied by handle 40 isoffset or concentrated to jaw member 110 to cause jaw member 110 toover-travel past parallel and cause jaw member 120 to deflect.

In one embodiment, the clamping pressure exceeds 16 kg/cm² to startinitial deflection of the second jaw member 120 about the living hinge127 with respect to the longitudinal axis “A”. While in both theapproximated position or the over-compressed position with jaw member120 deflected to exposed knife 184, a series of stop members (notexplicitly shown) disposed along the sealing surfaces 112, 122 of one orboth jaw members, 110, 120 respectively, are configured to maintain agap distance between jaw members 110 and 120 in the range of about 0.001inches to about 0.006 inches. As a result, the over-compressive force ofthe handle 40 in the second position is concentrated to deflect jawmember 120 and expose knife 184 and does not necessarily affect thecompressive force against the tissue grasped between jaw members 110 and120.

When the jaw member 120 deflects about the living hinge 127, knife 184is exposed and acts to sever tissue disposed between the jaw members 110and 120. More particularly, knife 184 is coupled to flange 124 andextends therefrom into a channel 129 defined within jaw member 120. Asthe drive pin 80 is pulled proximally past the approximated position andjaw member 110 exerts an over-compressive force against jaw member 120,jaw member 120 deflects against the bias of the living hinge 127 at anangle α relative to the longitudinal axis “A”.

As jaw member 120 deflects, both jaw members 110 and 120 are forced pastparallel with longitudinal axis “A”. Moreover, as jaw member 120deflects, knife 184 is exposed and projects from channel 129 throughtissue disposed between the jaw members 110 and 120 and into acorresponding channel 119 defined in jaw member 110 in verticalregistration with channel 129. When handle 40 is released, the drive pin80 retracts distally to an at-rest position forcing the jaw m embers 110and 120 to the spaced-apart position. As a result thereof, theover-compressive force against jaw member 120 is released and jaw member120 returns to a position parallel with longitudinal axis “A” under thereturn bias of living hinge 127. The severed and treated tissue may thenbe removed from between jaw members 110 and 120.

Referring to FIGS. 1-2D, the use and operation of forceps 10 forgrasping, treating and/or cutting tissue, is described. FIGS. 1 and 2Ashow jaw members 110, 120 disposed in the spaced-apart position suchthat end effector assembly 100 may be maneuvered into position so tissuemay be grasped, treated, e.g., sealed, and/or cut. Movable handle 40 iscompressed, or pulled proximally relative to fixed handle 50 such thatjaw member 110 is pivoted relative to jaw member 120 from thespaced-apart position to the approximated position to grasp tissuetherebetween, as shown in FIG. 2B. In this approximated position, energymay be supplied, e.g., via activation of switch 4, to plate 112 of jawmember 110 and/or plate 122 of jaw member 120 and conducted throughtissue to treat tissue, e.g., to effect a tissue seal or otherwise treattissue in the bipolar mode of operation. In this instance the jawmembers 110 and 120 may be reopened by releasing handle 40 to releasethe tissue.

Alternatively, the handle 40 may be further compressed to the secondposition to apply an over-compressive force to the jaw members 110 and120 to over-travel jaw member 110 against jaw member 120 pastlongitudinal axis “A” thereby deflecting jaw member 120 relative tolongitudinal axis “A” and exposing knife 184 to sever the tissuedisposed between jaw members 110 and 120. Jaw members 110 and 120 may bereopened by releasing handle 40 to release the tissue.

In one embodiment, the over-travel of jaw member 110 against jaw member120 causes jaw member 120 to deflect in a tip-biased manner, therebyexposing a distal end of the knife 184 initially and cutting tissue in adistal-to-proximal manner.

Alternatively, movable handle 40 may be compressed, or pulled proximallyrelative to fixed handle 50 such that jaw member 110 is pivoted relativeto jaw member 120 from the spaced-apart position to the approximatedposition and further compressed to the second position to over-compressjaw member 110 against jaw member 120, as shown in FIG. 2C. In thisover-compressed position, the knife 184 is exposed and will sever thetissue disposed between jaw members 110 and 120. As can be appreciated,this allows the surgeon to utilize the forceps 10 in a conventionalcutting manner without energizing or treating tissue.

In yet another embodiment, movable handle 40 may be compressed relativeto fixed handle 50 such that jaw member 110 is pivoted relative to jawmember 120 from the spaced-apart position to the approximated positionand further compressed to the second position to over-compress jawmember 110 against jaw member 120, as shown in FIG. 2C. In thisover-compressed position, simultaneous (or substantially simultaneously)the knife 184 is exposed to cut tissue between jaw members 110 and 120while energy is being supplied via activation of switch 4 to the tissue.As can be appreciated this allows the user to grasp, cut and treattissue at relatively the same time or at least substantiallysimultaneously cut and treat tissue at the same time.

One or more safety features may be employed to prevent exposure of theknife 184 prior to activation of energy. For example, switch 4 may beelectrically connected to a mechanical stop (not shown) that preventsthe exposure of the knife 184 prior to activating energy. One embodimentmay include the activation switch 4 being disposed in the pathway of themovable handle 40 such that switch 4 must be deployed to move handle 40past the approximated position. In another embodiment, a mechanicalrelease (not shown) is employed with activation switch 4 that releaseshandle 40 to permit movement past the approximated position.

When tissue cutting is complete, handle 40 may be released to allow jawmembers 110 and 120 to initially return to a parallel configurationalong longitudinal axis “A” thereby allowing knife 184 to retract backinto channel 129. Further release of handle 40 moves jaw members 110,120 back to the spaced-apart position (FIG. 2A) to release the treatedand/or divided tissue.

The various embodiments disclosed herein may also be configured to workwith robotic surgical systems and what is commonly referred to as“Telesurgery.” Such systems employ various robotic elements to assistthe surgeon and allow remote operation (or partial remote operation) ofsurgical instrumentation. Various robotic arms, gears, cams, pulleys,electric and mechanical motors, etc. may be employed for this purposeand may be designed with a robotic surgical system to assist the surgeonduring the course of an operation or treatment. Such robotic systems mayinclude remotely steerable systems, automatically flexible surgicalsystems, remotely flexible surgical systems, remotely articulatingsurgical systems, wireless surgical systems, modular or selectivelyconfigurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consolesthat are next to the operating theater or located in a remote location.In this instance, one team of surgeons or nurses may prep the patientfor surgery and configure the robotic surgical system with one or moreof the instruments disclosed herein while another surgeon (or group ofsurgeons) remotely control the instruments via the robotic surgicalsystem. As can be appreciated, a highly skilled surgeon may performmultiple operations in multiple locations without leaving his/her remoteconsole which can be both economically advantageous and a benefit to thepatient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pairof master handles by a controller. The handles can be moved by thesurgeon to produce a corresponding movement of the working ends of anytype of surgical instrument (e.g., end effectors, graspers, knifes,scissors, etc.) which may complement the use of one or more of theembodiments described herein. The movement of the master handles may bescaled so that the working ends have a corresponding movement that isdifferent, smaller or larger, than the movement performed by theoperating hands of the surgeon. The scale factor or gearing ratio may beadjustable so that the operator can control the resolution of theworking ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback tothe surgeon relating to various tissue parameters or conditions, e.g.,tissue resistance due to manipulation, cutting or otherwise treating,pressure by the instrument onto the tissue, tissue temperature, tissueimpedance, etc. As can be appreciated, such sensors provide the surgeonwith enhanced tactile feedback simulating actual operating conditions.The master handles may also include a variety of different actuators fordelicate tissue manipulation or treatment further enhancing thesurgeon's ability to mimic actual operating conditions.

Referring to FIG. 4, a medical work station is shown generally as workstation 1000 and may generally include a plurality of robot arms 1002,1003; a control device 1004; and an operating console 1005 coupled withcontrol device 1004. Operating console 1005 may include a display device1006, which may be set up in particular to display three-dimensionalimages; and manual input devices 1007, 1008, by means of which a person(not shown), for example a surgeon, may be able to telemanipulate robotarms 1002, 1003 in a first operating mode.

Each of the robot arms 1002, 1003 may include a plurality of members,which are connected through joints, and an attaching device 1009, 1011,to which may be attached, for example, a surgical tool “ST” supportingan end effector 1100, in accordance with any one of the embodimentsdisclosed hereinabove.

Robot arms 1002, 1003 may be driven by electric drives (not shown) thatare connected to control device 1004. Control device 1004 (e.g., acomputer) may be set up to activate the drives, in particular by meansof a computer program, in such a way that robot arms 1002, 1003, theirattaching devices 1009, 1011 and thus the surgical tool (including endeffector 1100) execute a desired movement according to a movementdefined by means of manual input devices 1007, 1008. Control device 1004may also be set up in such a way that it regulates the movement of robotarms 1002, 1003 and/or of the drives.

Medical work station 1000 may be configured for use on a patient 1013lying on a patient table 1012 to be treated in a minimally invasivemanner by means of end effector 1100. Medical work station 1000 may alsoinclude more than two robot arms 1002, 1003, the additional robot armslikewise being connected to control device 1004 and beingtelemanipulatable by means of operating console 1005. A medicalinstrument or surgical tool (including an end effector 1100) may also beattached to the additional robot arm. Medical work station 1000 mayinclude a database 1014, in particular coupled to with control device1004, in which are stored, for example, pre-operative data frompatient/living being 1013 and/or anatomical atlases.

From the foregoing and with reference to the various drawing figures,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. While several embodiments of the disclosure have been shownin the drawings, it is not intended that the disclosure be limitedthereto, as it is intended that the disclosure be as broad in scope asthe art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

What is claimed is:
 1. A surgical instrument, comprising: a housinghaving an elongated shaft that extends therefrom; a handle pivotablycoupled to the housing and moveable relative thereto; an end effectorassembly including first and second jaw members, the first jaw memberpivotably attached to a distal end of the shaft and the second jawmember extending along a longitudinal axis defined therethrough andfixed to the distal end of the shaft by a living hinge, the first jawmember, upon actuation of the handle relative to the housing, is movablerelative to the second jaw member between a spaced-apart position, anapproximated position for grasping tissue between the first and secondjaw members, and a second position for providing an over-compressiveforce to the jaw members; and a knife disposed within a channel definedwithin the second jaw member, wherein, when the handle is initiallyactuated relative to the housing, the first jaw member is moved from thespaced-apart position to the approximated position to grasp tissuebetween jaw members, and when the handle is further actuated from theapproximated position to the second position, the first jaw memberover-travels past the longitudinal axis to provide an over-compressiveforce to the jaw members such that the second jaw member deflectsrelative to the longitudinal axis against the bias of the living hingeexposing the knife from the channel to cut tissue grasped between jawmembers.
 2. The surgical instrument according to claim 1, furthercomprising a drive rod extending through the shaft, the drive rodincluding a drive pin at a distal end thereof, wherein actuation of thedrive rod moves the first jaw member relative to the second jaw member.3. The surgical instrument according to claim 2, wherein the first jawmember includes a flange that extends proximally therefrom, the flangeincluding an aperture defined therein for receiving a pivot pin, thefirst jaw member rotatable about the pivot pin upon actuation of thedrive rod.
 4. The surgical instrument according to claim 3, wherein theflange includes a cam slot defined therein, the drive pin moveablewithin the cam slot to move the first jaw member relative to the secondjaw member.
 5. The surgical instrument according to claim 1, wherein, inthe approximated position, the jaw members grasp tissue with a clampingpressure in the range of about 3 kg/cm² to about 16 kg/cm².
 6. Thesurgical instrument according to claim 5, wherein when the clampingpressure between jaw members exceeds 16 kg/cm², the second jaw memberdeflects relative to the longitudinal axis to expose the knife.
 7. Thesurgical instrument according to claim 1, wherein the first jaw memberincludes a channel defined therein in vertical registration with thechannel defined within the second jaw member, the channel defined in thefirst jaw member configured to receive the knife as the first jaw memberover travels past the longitudinal axis and the second jaw memberdeflects about the living hinge.
 8. The surgical instrument according toclaim 1, wherein the over travel of the first jaw member against thesecond jaw member causes the second jaw member to deflect in atip-biased manner thereby initially exposing a distal end of the knifeand cutting tissue in a distal-to-proximal manner as the knife isfurther exposed.
 9. A surgical instrument, comprising: an end effectorassembly including first and second jaw members, the first jaw memberpivotable relative to the second jaw member, the second jaw memberextending along a longitudinal axis defined therethrough and including aliving hinge at a proximal end thereof, the first jaw member movablerelative to the second jaw member between a spaced-apart position, anapproximated position for grasping tissue between the first and secondjaw members, and a second position for providing an over-compressiveforce to the jaw members; and a knife disposed within a channel definedwithin the second jaw member, wherein when the first jaw member is movedfrom the spaced-apart position to the approximated position to grasptissue between jaw members, and further moved from the approximatedposition to the second position to provide an over-compressive force tothe jaw members, the first jaw member over-travels past the longitudinalaxis and the second jaw member deflects relative to the longitudinalaxis against the bias of the living hinge exposing the knife from thechannel to cut tissue disposed between jaw members.
 10. The surgicalinstrument according to claim 9, wherein, in the approximated position,the jaw members grasp tissue with a clamping pressure in the range ofabout 3 kg/cm² to about 16 kg/cm².
 11. The surgical instrument accordingto claim 10, wherein when the clamping pressure between jaw membersexceeds 16 kg/cm², the second jaw member deflects relative to thelongitudinal axis to expose the knife.
 12. The surgical instrumentaccording to claim 9, wherein the first jaw member includes a channeldefined therein in vertical registration with the channel defined withinthe second jaw member, the channel defined in the first jaw memberconfigured to receive the knife as the first jaw member over-travelspast the longitudinal axis and the second jaw member deflects about theliving hinge.
 13. The surgical instrument according to claim 9, whereinthe over travel of the first jaw member against the second jaw membercauses the second jaw member to deflect in a tip-biased manner therebyinitially exposing a distal end of the knife and cutting tissue in adistal-to-proximal manner as the knife is further exposed.
 14. A methodfor treating and cutting tissue, comprising: actuating a handle of asurgical instrument to grasp tissue between a pair of first and secondjaw members of an end effector assembly under a first pressure; applyingelectrosurgical energy to the jaw members to treat tissue graspedbetween the end effectors; further actuating the handle to cause thefirst jaw member to over-travel past a longitudinal axis defined throughthe second jaw member thereby causing the second jaw member to deflectabout a living hinge relative to the longitudinal axis and expose aknife for severing tissue grasped between the jaw members.